A. Field of the Invention
The present invention relates to irrigated catheter assemblies. The present invention further relates to ablation electrodes and assemblies, including electrode assemblies having distal irrigation fluid flow. The present invention further relates to ablation electrode assemblies having at least one temperature sensing device and a mechanism for irrigating the ablation assembly and targeted areas. The present invention further relates to methods for improved assembly and accurate measurement and control of the electrode temperatures while effectively irrigating the device and target areas.
B. Background Art
Electrophysiology catheters are used for an ever-growing number of procedures. Catheters are used for diagnostic, therapeutic, and ablative procedures, to name just a few examples. Typically, a catheter is manipulated through the patient's vasculature and to the intended site, for example, a site within the patient's heart. The catheter typically carries one or more electrodes, which may be used for ablation, diagnosis, or other treatments.
There are a number of methods used for ablation of desired areas, including for example, radiofrequency (RF) ablation. Ablation may be facilitated by transmission of energy from an electrode assembly to ablate tissue at the target site. Because ablation may generate significant heat, which if not controlled can result in excessive tissue damage, such as steam pop, tissue charring, and the like, it is desirable to include a mechanism to irrigate the target area and the device with biocompatible fluids, such as water or saline solution. The use of irrigated ablation catheters can also prevent the formation of soft thrombus and/or blood coagulation.
Typically, there are two classes of irrigated electrode catheters, open and closed irrigation catheters. Closed ablation catheters usually circulate a cooling fluid within the inner cavity or lumen provided by the ablation electrode. Open ablation catheters typically deliver the cooling fluid through open outlets or openings to a surface of the electrode. Open ablation catheters use an inner cavity or lumen of the electrode, as a manifold to distribute saline solution, or other irrigation fluids known to those skilled in the art, to one or more passageways that lead to an opening/outlet provided on the surface of the electrode. The cooling fluid thus flows through the outlets of the passageways onto the electrode member. This flow through the electrode tip lowers the temperature of the tip during operation, often making accurate monitoring and control of the ablative process more difficult.
In general, open irrigated ablation catheters may improve the function and safety associated with catheter ablation by preventing protein aggregation and blood coagulation. A particular area of the electrode/catheter where the formation of coagulum or thrombus may occur during ablation procedures is at the distal end or tip of the electrode.